As the recording density of the magnetic disk increases, it is important to reduce the clearance between the head element flying above the magnetic disk. A thermal fly height control (TFC) disposed in a head slider adjusts the clearance by using the heater to heat the head element.
In the manufacturing test for a hard disk drive (HDD), power to the TFC gradually increases. If contact is detected between the head slider and the magnetic disk, the power corresponding to the specified clearance is subtracted from the applied power and stored as the standard applied power for that head. This calibration procedure is referred to as manufacturing touch down detection. However, contamination within the HDD can skew the results of the manufacturing touch down detection.
The drawings referred to in this description should be understood as not being drawn to scale except if specifically noted.